Hi All!
I was looking at the beta-sheet of the Cranbin protein (1CRN). This
beta-sheet is composed of 2 strands (residues 1 to 4 and 32 to 35).
H-bonds partners in the beta-sheets are 1 <-> 35 and 3 <-> 33, like:
A)
1 <-> 35
2 34
3 <-> 33
4 32
Q. Is there any reasons why the h-bonding is such?
Is there any counter to the possibility of having h-bonds partners 2
<-> 34 and 4 <-> 32 instead of 1 <-> 35 and 3<-> 33, like:
B)
1 35
2 <-> 34
3 33
4 <-> 32
this would inverse the side-chain orientation (the ones on top of the
sheet will now be on the bottom and vice-versa) impacting on the
surrounding side-chains, but if we look at only the sheet itself, is
there a reason why would nature prefer setup A over setup B?
Thanks for your time,
Marc.